α-PGG has been shown to possess anti-diabetic and other bioactivities that make it a target for the development of new drugs. Since is does not occur in nature, it must be prepared by a multi-step synthesis. Currently known procedures to synthesize α-PGG comprise two main steps: an initial acylation reaction generates benzyl group-protected α-PGG. This precursor must be isolated in order to obtain pure α-PGG in the final hydrogenation reaction. The first step (acylation) produces large amounts of side products that are very difficult to remove. The most important of these unwanted chemicals are the β-isomer of the PGG precursor, dialkyl urea, and N-acylurea derivatives. Chromatography, which is quite expensive, is the only technique that allows for the purification of benzyl-group protected α-PGG. Only gram quantities of the target compound can be produced. The high costs of chromatography and the difficulties in scale-up procedures suitable for producing kilogram to ton quantities of product preclude industrial application of the procedure.
Accordingly, a need exists for better methods of producing the precursors of α-PGG. The new methods should eliminate the need for chromatography, and should be amenable to scaling up to kilogram or ton quantities.